Gypsum Wall Damage Investigation

Damage to gypsum wallboard can be an indicator of the level of lateral movement experienced during an earthquake. A series of 17 experiments conducted at San Jose State University recorded common failure modes of gypsum wallboard typical of construction in woodframe structures. These experimental tests showed the relationship between lateral movement of the ceiling and floor and the type and extent of the resulting damage. This knowledge can be used to make field judgments about the level of movement that may have resulted during an earthquake or other severe lateral loading. This paper will review the damage thresholds observed during the experimental testing and the fragility curves developed for each damage threshold. BACKGROUND Gypsum wallboard has a wide variety of uses in modern construction. The primary purpose of wallboard is the interior surface for wood framed walls or ceilings in residential construction. Wallboard is often used as the interior finish surface on vertical surfaces of commercial and institutional construction, often supported by steel studs. The primary purpose of wallboard is to provide a durable surface for architectural finish. In addition wallboard on bearing walls is expected to provide buckling stability for the framing. In certain situations, wallboard may be considered the lateral force resisting system for the structure. In addition, wallboard may be a significant part of the fire control system of the structure. In the past, research has been conducted on the lateral shear strength of wallboard systems, particularly those with small spacing between fasteners, thus qualifying their use as a portion of the lateral force resisting system [Merrick 1997, Karacabeyli and Ceccotti 1996, Oliva 1990; Zacker and Gray 1985, Adams, 1974]. This paper focuses on the role of wallboard as an architectural finish for vertical walls, particularly those built on wood framing for single-family residential construction. Of particular interest is the damage of the wallboard due to lateral forces applied at the top level. Damage patterns of wallboard are related to interstory drift and the potential use of damage patterns as a means of assessing potential damage to underlying structural members is discussed. As a result of this focus, most of the discussion is related to the visible damage to wallboard. Additional information about the testing and physical properties of wallboard research conducted by the authors is available in other publications [McMullin and Merrick, 2007, 2002].